In the manufacture of wires for use as conductors in the telecommunications and power distribution industries, it is desirable to know the relative solid solution contaminate content of the conductor material in order to determine to what degree the wire must be annealed to meet flexibility and electrical resistance requirements. If an insufficient amount of power is applied during the annealing process the wire is insufficiently annealed thus reducing its ductility, subjecting it to breakage, and rendering it with excessive electrical resistance. Conversely, if an excessive amount of power is applied during the annealing process a risk of breakage from burn out occurs as well as a waste of energy.
There are, of course, several ways in which the composition of a metallic wire may be anaylzed. For example, the wire may be subject to spectrographic analysis which can render a complete quantitative and qualitative determination of the wire composition. Such a detailed and sophisticated analysis, however, is unneeded and actually inadequate for determining the amount of energy to be applied for annealing. Since such anaylses do not distinguish between the various forms in which impurities are present, such as particulate, inter-metallic compound, or solid solution. These various forms occur in accordance with the thermal history of the wire. A copper wire containing one impurity in particulate form, for example, will anneal better than one containing the same quantity of that impurity in solid solution form, thus causing a substantial degradation in wire annealability.
Another well known approach in determining the degree of purity of conductive wire material involves the use of electrical conductivity testing. Again, however, the conductivity of a metallic wire is a function of both the proportion as well as the composition of the impurities present. The measurement of conductivity alone therefore can lead to an erroneous determination of material purity as far as annealing characteristics are concerned.
It is thus seen that a need exists for a method of determining the solid solution contaminate content of wire conductive material which is accurate, practical for use in a manufacturing environment, and not unduly sophisticated as by producing an analysis of the impurities themselves. It is to this task to which the present invention is primarily directed.